High-performance lexer generation using compile-time DFA construction, combined token definitions, lookup/jump-table optimizations, regex and literal tokens, loop unrolling, and no-backtracking.
This is a Kotlin Multiplatform line-by-line transliteration port of maciejhirsz/logos.
Original Project: This port is based on maciejhirsz/logos. All design credit and project intent belong to the upstream authors; this repository is a faithful port to Kotlin Multiplatform with no behavioural changes intended.
This is an in-progress port. The goal is feature parity with the upstream Rust crate while providing a native Kotlin Multiplatform API. Every Kotlin file carries a // port-lint: source <path> header naming its upstream Rust counterpart so the AST-distance tool can track provenance.
maciejhirsz/logosThe text below is reproduced and lightly edited from
https://github.com/maciejhirsz/logos. It is the upstream project's own description and remains under the upstream authors' authorship; links have been rewritten to absolute upstream URLs so they continue to resolve from this repository.
Create ridiculously fast Lexers.
Logos has two goals:
To achieve those, Logos:
For more examples and documentation, please refer to the Logos handbook or the crate documentation.
Ridiculously fast!
test identifiers ... bench: 647 ns/iter (+/- 27) = 1204 MB/s
test keywords_operators_and_punctators ... bench: 2,054 ns/iter (+/- 78) = 1037 MB/s
test strings ... bench: 553 ns/iter (+/- 34) = 1575 MB/s
Logos is very much a labor of love. If you find it useful, consider getting me some coffee. ☕
If you'd like to contribute to Logos, then consider reading the Contributing guide.
Logos welcome any kind of contribution: bug reports, suggestions, or new features!
Please use the issues or pull requests tabs, when appropriate.
To release a new version, follow the RELEASE-PROCESS
This code is distributed under the terms of both the MIT license and the Apache License (Version 2.0), choose whatever works for you.
See LICENSE-APACHE and LICENSE-MIT for details.
dependencies {
implementation("io.github.kotlinmania:logos:0.2.0")
}
./gradlew build
./gradlew test
See AGENTS.md and CLAUDE.md for translator discipline, port-lint header convention, and Rust → Kotlin idiom mapping.
This Kotlin port is distributed under the same MIT license as the upstream maciejhirsz/logos. See LICENSE (and any sibling LICENSE-* / NOTICE files mirrored from upstream) for the full text.
Original work copyrighted by the logos authors.
Kotlin port: Copyright (c) 2026 Sydney Renee and The Solace Project.
Thanks to the maciejhirsz/logos maintainers and contributors for the original Rust implementation. This port reproduces their work in Kotlin Multiplatform; bug reports about upstream design or behavior should go to the upstream repository.
use logos::Logos;
// Ignore this regex pattern between tokens
enum Token {
// Tokens can be literal strings, of any length.
Fast,
Period,
// Or regular expressions.
Text,
}
fn main() {
let mut lex = Token::lexer("Create ridiculously fast Lexers.");
assert_eq!(lex.next(), Some(Ok(Token::Text)));
assert_eq!(lex.span(), 0..6);
assert_eq!(lex.slice(), "Create");
assert_eq!(lex.next(), Some(Ok(Token::Text)));
assert_eq!(lex.span(), 7..19);
assert_eq!(lex.slice(), "ridiculously");
assert_eq!(lex.next(), Some(Ok(Token::Fast)));
assert_eq!(lex.span(), 20..24);
assert_eq!(lex.slice(), "fast");
assert_eq!(lex.next(), Some(Ok(Token::Text)));
assert_eq!(lex.slice(), "Lexers");
assert_eq!(lex.span(), 25..31);
assert_eq!(lex.next(), Some(Ok(Token::Period)));
assert_eq!(lex.span(), 31..32);
assert_eq!(lex.slice(), ".");
assert_eq!(lex.next(), None);
}
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